Metal Injection Molding
Metal Injection Molding (MIM) is a net-shape or near-net-shape process for the fabrication of complex metal parts. In general, the fabrication of complex metal parts requires the use of several traditional process technologies, or the assembly of subparts obtained from different processes to create a finished assembly.
The use of MIM technology makes it possible to use a single process, reduce costs and produce complex parts without assembly; it also offers the potential to obtain 3D forms of a complexity analogous to that obtained with thermoplastics injection molding, but with mechanical specifications approaching those of parts machined from metal stock.
The raw material is a metal powder with a granularity of less than 30µm (normally 80%<20µm). This powder is mixed with a binder to form the feedstock. The feedstock, using a technology which is very similar to injection molding of thermoplastics, is injected into a die to create the green part. The green part is subjected to debinding, which extracts the binder, and sintering, to obtain a finished product with density in the range 97.8% to 98.5%. Such high densities are obtained with sintering due to the uniformity of the structure of the green part obtained from injection molding: this uniformity means that morphological distortions are eliminated, even when the density is augmented to such high levels by sintering (in classical sintering the molding process is along one axis and this results in uneven density of the green part, meaning that such high densities and performance are not possible).

General criteria
Comparison with other technologies
Tolerances
Borings
Threads
Uniform cross-sections
Injection
Surface finish
Assembly of green parts
Materials
Mechanical characteristics